Liquid separating devices (or simply “separators”), such as manure separators for example, and the cascading press roller configurations used therewith, are known in the art, as shown in FIGS. 1-4, for example.
Also known to the Applicant are the following US patent and patent applications which describe various other types of conventional separating mechanisms and/or roller assemblies: U.S. Pat. Nos. 1,339,600; 3,531,404; 3,699,881; 3,873,450; 3,906,853; 3,971,310; 4,070,175; 4,775,472; 4,879,034; 4,940,500; 4,986,910; 4,997,579; 5,022,989; 5,073,200; 5,268,100; 5,545,333; 6,003,684; 7,314,141 B1; 7,381,329 B1; 7,651,619 B2; 2001/0046456 A1; 2005/0279711 A1; 2007/0193063 A1; and 2010/0032384 A1.
It is also known that a substantial problem associated with conventional liquid separating systems is that remoistening is very present when carrying out liquid separation (“dewatering”) by compression under rollers. Indeed, material is fed between rollers, the solid exiting between the rollers and the liquid going into the rollers. The phenomenon of surface tension in the liquids causes the liquid extracted and going through the porosities of the roller to not be entirely extracted since an amount of water remains within the porosities. When the matter exits from between two rollers, these droplets captured in the porosities of the roller return into the material to be processed, which is not desirable.
Another substantial problem associated with conventional liquid separating systems is that the extracting of liquid is also influenced by the pressure applied to the matter to be processed. Since the matter enters in a random fashion, it often occurs that certain areas of the bed have less matter, and therefore practically no compression pressure is available while it is distributed on the environing matter.
There is thus a need in the art to improve the drying rate of the fibre (“separation rate”) being possible, and to also limit the “remoistening” of the fibre with is common to most conventional systems.
It should be noted also that the treatment equipment must generate an acceptable drawing rate for use on extracted solids as litter. The use of a solid as litter may be considered when the proportion of dry matter is greater than 29%. The current conventional technologies of “screw press” type succeed in obtaining drying rates in this order, however their mechanical configuration damages the fibre which constitutes the solid matter. The behaviour of the bacteria in the litter and the comfort of the animals is thus compromised. It should be noted also that the behaviour of the matter to be processed is not linear. As a consequence, it is much easier to go from a rate of 29 to 32%, then it is to go from a rate of 31 to 34% of dry matter. For each additional percentage of separation, the effort required for the treatment increases exponentially.
Tests have demonstrated that it is possible, with conventional systems of the prior art, to obtain a rate of solid matter in the order of about 31% (more particularly with roller press) to about 35% (particularly with “screw press” type configurations). However, further to undesirable properties of the extracted matter (type of fibre and chemical composition), the results have shown not to be constant and a lot of mechanical failures and/or premature wear was present, given strong compression forces necessary. It is thus not viable, by using the conventional systems of the prior art, to efficiently use the solid portion extracted as litter. Cultivators and breeders are thus constrained to use other solutions in order to ensure the comfort of animals.
Another important consideration rests on the application of the product on the market. A viable solution must thus be low cost and offer the possibility of treating the matter of small farms while allowing the possibility of expansion thereof. The efficiency rates described hereinabove relate to the manure treatment of bovine breeding. It should be considered that the above-mentioned drawbacks of the prior art are also present in different environments of separation, such as in the food industry, the separation of municipal waste, specialised treatment plans, etc.
Roller separators are also well known in the art. Indeed, in the farming field for example, in order to extract water away from material to be treated, such as manure for example, the material is often inserted into a series of rollers that press water out of the material. However, the rollers are generally equal in length, from one stage to another, and the thickness of the material being treated or “pressed” is always the same from one stage to another, which not only does not allow to efficiently extract water from the material, but can sometimes lead to a reabsorbing effect (water may be absorbed back into the material), which is obviously undesirable, as aforementioned.
Hence, in light of the above-discussed, there is a need for an improved liquid separating device, which by virtue of its design and components, would be able to overcome or at the very least minimize some of the above-mentioned prior art problems and drawbacks.